A method for quantitatively evaluating casing wall thickness damage
By analyzing the common characteristics of the reflected waves from casing damage, extracting the arrival time difference between the casing and the reflected waves from damage, and combining this with the ultrasonic propagation velocity, an accurate quantitative evaluation of casing wall thickness damage was achieved. This solved the problem of calculation errors under severe casing damage and ensured production safety.
Patent Information
- Application Number
- CN202411013186.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-26
- Publication Date
- 2025-11-28
- Estimated Expiration
- 2044-07-26
AI Technical Summary
Existing technologies have significant errors in calculating the casing wall thickness when the casing is severely damaged, leading to misjudgments of minor or no damage, which poses a production safety hazard.
By analyzing the common characteristics of reflected waves under casing damage, casing reflected waves and damage reflected waves are extracted, the arrival time difference between the two is calculated, and combined with the ultrasonic propagation velocity, the degree of casing wall thickness damage is quantitatively evaluated.
This method achieves accurate calculation of casing wall thickness under severe damage conditions, solves the error problem of conventional methods, and ensures the accuracy and safety of evaluation results.
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Figure CN118960636B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of casing integrity evaluation in wellbore, in particular to a casing wall thickness damage quantitative evaluation method. BACKGROUND
[0002] Wellbore integrity is a key factor for the safety of oil and gas well production. As the main component of wellbore, the structural integrity and uniformity of casing wall thickness directly affect the production efficiency and safety of oil and gas well. With the increase of service time, casing may be affected by various factors, resulting in different damage types, such as chemical or electrochemical corrosion of the medium in the pipe, scratches and depressions caused by friction and collision of production equipment and casing, deformation and rupture caused by mechanical stress of formation movement, etc. Therefore, it is of great significance to quantitatively evaluate the wall thickness of damaged casing. Accurate assessment of casing wall thickness damage can ensure long-term stable operation of wellbore, reduce production risk and environmental impact, improve economic benefits and ensure production safety.
[0003] Ultrasonic pulse echo measurement technology, as a non-destructive testing method, is widely used in the integrity detection of oil well casing. At present, the conventional casing wall thickness calculation method has been proposed, which is to extract the resonance frequency of the resonance wave in the reflected wave, that is, to select the frequency value corresponding to the 'concave point' of the full wave spectrum to calculate the casing thickness. By comparing the original casing thickness, the casing damage thickness is calculated. When the casing is undamaged or slightly damaged, the resonance wave is not affected, the resonance frequency extraction is not prone to error, and the calculated casing thickness value is accurate, so the casing damage thickness is accurate. However, this method also has problems: when the casing is severely damaged, the resonance wave is greatly attenuated or even there is no resonance wave, the resonance frequency extraction is not accurate, resulting in distortion of wall thickness calculation, and the casing damage thickness has a large error with the actual damage thickness.
[0004] In the prior art, when the casing is severely damaged, the conventional casing wall thickness calculation method will result in a large error in wall thickness calculation, and the casing that has been seriously perforated may be misjudged as a slight wall thickness damage or no damage, causing serious safety problems in operation and production. SUMMARY
[0005] Based on the above technical problems, the present application provides a casing wall thickness damage quantitative evaluation method, which analyzes the common characteristics of reflected waves under casing damage, extracts two wave modes existing in reflected waves: casing reflected waves and damage reflected waves, and quantitatively evaluates the damage wall thickness according to the information contained in the two, the specific technical scheme is as follows.
[0006] A casing wall thickness damage quantitative evaluation method, comprising the following steps:
[0007] Step S1: install the ultrasonic measuring instrument to emit ultrasonic pulses, during the measurement, the central axis of the ultrasonic measuring instrument rises along the direction of the casing, and the waveform Wave is measured according to the fixed circumferential resolution and axial resolution;
[0008] Step S2: calculate the ultrasonic propagation speed V of the medium in the casing;
[0009] Step S3: pre-process the measured waveform Wave to determine the sound source function Source of the ultrasonic instrument;
[0010] Step S4: calculate using the measured waveform Wave and the sound source function Source, shift the sound source function Source data, multiply and sum the corresponding waveform data to obtain the cross-correlation result CorreWave of the waveform Wave and the sound source function Source;
[0011] Step S5: envelope the cross-correlation result CorreWave and perform low-pass filtering to locate the maximum peak value Peak1 and the second maximum peak value Peak2 of the two reflection waves that may occur in the received waveform, and calculate the time difference DeltaTime corresponding to the two peak values;
[0012] Step S6: according to the time difference DeltaTime of the two wave peaks and the ultrasonic propagation speed V in the casing medium, calculate the damage thickness Thick, and the calculation formula is:
[0013] Thick = DeltaTime x V.
[0014] Specifically, the ultrasonic measuring instrument comprises an ultrasonic probe which emits ultrasonic pulses perpendicular to the inner wall of the casing.
[0015] Specifically, the step S2 specifically comprises the following sub-steps:
[0016] Step S21: use the long-short time window method to extract the first wave arrival time ArriveTime of different azimuth pulse echo waveforms and the opposite direction first wave arrival time OppositeTime, and calculate the average value AverageTime of the sum of the first wave arrival time ArriveTime and the opposite direction first wave arrival time OppositeTime measured continuously at the same depth for one week, which is expressed as:
[0017] AverageTime = ArriveTime + OppositeTime;
[0018] Step S22: based on the casing diameter Dcasing and the probe rotation track diameter D of the ultrasonic measuring instrument, the average value AverageTime calculated based on the first wave arrival time of the pulse echo and the opposite direction first wave arrival time, the ultrasonic propagation speed V is obtained, and the calculation formula is:
[0019]
[0020] Specifically, the determination of the sound source function Source of the ultrasonic instrument in the step S3 is specifically:
[0021] finding a time PeakTime corresponding to a maximum value of the single-channel waveform, performing Fourier transform FFT on the waveform, and extracting a center frequency f and a corresponding main period T of the waveform;
[0022] extracting a corresponding sequence in a time range [Peaktime-T, PeakTime+T] before and after the maximum value of the waveform, and defining the sequence as the sound source function Source of the ultrasonic instrument.
[0023] Specifically, the low-pass filtering in the step S5 is specifically: using Hilbert transform to calculate an envelope EnvelopeWave of the cross-correlation result CorreWave, performing maximum absolute value normalization on the envelope, and simultaneously setting a corresponding Butterworth low-pass filter to perform low-pass filtering.
[0024] Specifically, the positioning of the wave peak value in the step S5 specifically includes:
[0025] positioning to a maximum wave peak value Peak1 of the waveform, and finding a second maximum wave peak value Peak2 before and after the maximum value of the waveform;
[0026] if the position of the maximum wave peak value Peak1 appears in front of the second maximum wave peak value Peak2, performing threshold value judgment on a value of the second maximum wave peak value Peak2, setting a threshold value as 0.15, and considering that there is no second maximum wave peak value if the value is lower than the threshold value;
[0027] if the position of the maximum wave peak value Peak1 appears behind the second maximum wave peak value Peak2, not performing any operation, and jumping to the step S6.
[0028] Specifically, the step S5 further includes: if there is no second maximum wave peak value, calculating a time span TimeWidth in which the waveform drops to 20% of the maximum value of the waveform, and specifically including:
[0029] if the time span TimeWidth is greater than a preset period number, there are two wave peaks and the two wave peaks overlap, the influence of the maximum value of the waveform is removed, the two maximum values Peak1 and Peak2 of the waveform are repositioned, and a time difference DeltaTime corresponding to the two peak values is calculated;
[0030] if the TimeWidth is less than a certain period number, considering that there is only one wave peak in the waveform, and outputting the DeltaTime result as -1.
[0031] The application provides a casing wall thickness damage quantitative evaluation method for an ultrasonic pulse echo measurement mode in a casing well, and is used for evaluating casing wall thickness of a damage position.
[0032] (1) The casing reflection wave and the damage reflection wave are positioned, the time difference of the two is extracted, the ultrasonic propagation speed in the casing medium is calculated, and the casing wall thickness damage degree is quantitatively evaluated. The method is completely not affected by instrument eccentricity, and the evaluation result is accurate.
[0033] (2) The evaluation result is accurate when the damage wall thickness is serious, and the distortion problem of the conventional wall thickness calculation method under the serious damage is solved. BRIEF DESCRIPTION OF DRAWINGS
[0034] Figure 1 It is a flow chart of the damage quantitative evaluation method provided by the application.
[0035] Figure 2 It is a casing damage physical model profile processed in the embodiment of the application. Eight damages are arranged on the inner wall of the casing, four damages with a diameter of 20 mm and four damages with a diameter of 40 mm, and the damage wall thicknesses are 3.36 mm, 5.36 mm, 6.36 mm and 7.36 mm.
[0036] Figure 3 It is a schematic diagram of the ultrasonic propagation speed calculation in the casing in the embodiment of the application.
[0037] Figure 4 It is a schematic diagram of the ultrasonic propagation speed calculation result in the casing in the experimental data in the embodiment of the application.
[0038] Figure 5 It is a schematic diagram of the selection of the sound source function in the experimental data in the embodiment of the application.
[0039] Figure 6 It is a schematic diagram of the Hilbert transform envelope extraction of the normal waveform in the experimental data in the embodiment of the application.
[0040] Figure 7is a schematic diagram of envelope extraction of abnormal waveform Hilbert transform of experimental data in the embodiment of the present application.
[0041] Figure 8 is a schematic diagram of processing results of continuous adjacent depth waveforms of experimental data in the embodiment of the present application.
[0042] Figure 9 is a schematic diagram of wall thickness damage evaluation results of experimental data in the embodiment of the present application.
[0043] Figure 10 is a schematic diagram of selection of sound source function of actual data in the embodiment of the present application.
[0044] Figure 11 is a schematic diagram of calculation results of ultrasonic propagation speed in casing in actual data in the embodiment of the present application.
[0045] Figure 12 is a schematic diagram of envelope extraction of normal waveform Hilbert transform of actual data in the embodiment of the present application.
[0046] Figure 13 is a schematic diagram of envelope extraction of abnormal waveform Hilbert transform of actual data in the embodiment of the present application.
[0047] Figure 14 is a schematic diagram of processing results of continuous adjacent depth waveforms of actual data in the embodiment of the present application.
[0048] Figure 15 is a schematic diagram of wall thickness damage evaluation results of actual data in the embodiment of the present application, wherein the left drawing is the evaluation results of a non-severe damage well section, and the right drawing is the evaluation results of a severe damage well section. DETAILED DESCRIPTION
[0049] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described with reference to the drawings.
[0050] The present application proposes a quantitative evaluation method for casing damage wall thickness in order to overcome the shortcomings of conventional casing damage wall thickness calculation methods. The present application analyzes the common features of reflected waves under casing damage conditions, extracts two wave modes existing in the reflected waves, i.e., casing reflected waves and damage reflected waves, and quantitatively evaluates the damage wall thickness according to the information contained in the two wave modes. The specific flow is shown in Figure 1
[0051] In the first embodiment,
[0052] The method specifically includes the following steps:
[0053] Step S1: install the ultrasonic measuring instrument to emit ultrasonic pulses, during the measurement, the central axis of the ultrasonic measuring instrument rises along the direction of the casing, and the waveform Wave is measured according to the fixed circumferential resolution and axial resolution;
[0054] Step S2: calculate the ultrasonic propagation speed V of the medium in the casing;
[0055] Step S3: pre-process the measured waveform Wave to determine the sound source function Source of the ultrasonic instrument;
[0056] Step S4: calculate using the measured waveform Wave and the sound source function Source, shift the sound source function Source data, multiply and sum corresponding to the waveform data, to obtain the cross-correlation result CorreWave of the waveform Wave and the sound source function Source;
[0057] Step S5: envelope the cross-correlation result CorreWave and perform low-pass filtering, locate the maximum peak value Peak1 and the second maximum peak value Peak2 of the two reflection waves that may occur in the received waveform, and calculate the time difference DeltaTime corresponding to the two peak values;
[0058] Step S6: according to the time difference DeltaTime of the two wave peaks and the ultrasonic propagation speed V in the casing medium, calculate the damage thickness Thick, the calculation formula is:
[0059] Thick = DeltaTime x V.
[0060] In this embodiment, the ultrasonic measuring instrument includes an ultrasonic probe, which emits ultrasonic pulses perpendicular to the inner wall of the casing.
[0061] In this embodiment, step S2 specifically includes the following sub-steps:
[0062] Step S21: use the long-short time window method to extract the first wave arrival time ArriveTime of the different azimuth pulse echo waveforms and the opposite direction first wave arrival time OppositeTime, and calculate the average value AverageTime of the sum of the first wave arrival time ArriveTime and the opposite direction first wave arrival time OppositeTime measured continuously at the same depth for one week, which is expressed as:
[0063] AverageTime = ArriveTime + OppositeTime;
[0064] Step S22: based on the casing diameter Dcasing and the probe rotation track diameter D of the ultrasonic measuring instrument, the average value AverageTime calculated based on the first wave arrival time of the pulse echo and the opposite direction first wave arrival time, the ultrasonic propagation speed V is obtained, and the calculation formula is:
[0065]
[0066] In the embodiment, the determination of the sound source function Source of the ultrasonic instrument in step S3 is specifically:
[0067] finding a time PeakTime corresponding to the maximum value of the single-channel waveform, performing Fourier transform FFT on the waveform, and extracting the center frequency f and the corresponding main period T of the waveform;
[0068] extracting a corresponding sequence in the time range [PeakTime-T, PeakTime+T] before and after the maximum value of the waveform, and defining the sequence as the sound source function Source of the ultrasonic instrument.
[0069] In the embodiment, the low-pass filtering in step S5 is specifically: using Hilbert transform to calculate the envelope EnvelopeWave of the cross-correlation result CorreWave, performing maximum absolute value normalization on the envelope, and setting a corresponding Butterworth low-pass filter to perform low-pass filtering.
[0070] The positioning of the peak value in step S5 specifically includes:
[0071] positioning to the maximum peak value Peak1 of the waveform, and finding a second maximum peak value Peak2 before and after the maximum value of the waveform;
[0072] if the position of the maximum peak value Peak1 appears in front of the second maximum peak value Peak2, performing threshold judgment on the value of the second maximum peak value Peak2, setting the threshold to 0.15, and considering that there is no second maximum peak value if the value is lower than the threshold;
[0073] if the position of the maximum peak value Peak1 appears behind the second maximum peak value Peak2, not performing any operation, and jumping to step S6.
[0074] Step S5 further includes: if there is no second maximum peak value, calculating a time span TimeWidth in which the waveform drops to 20% of the maximum value of the waveform, specifically including:
[0075] if the time span TimeWidth is greater than a preset number of periods, there are two wave peaks and the two wave peaks overlap, the influence of the maximum value of the waveform is removed, the two maximum values Peak1 and Peak2 of the waveform are repositioned, and the time difference DeltaTime corresponding to the two peak values is calculated;
[0076] if the TimeWidth is less than a certain number of periods, it is considered that the waveform only has one wave peak, and the output DeltaTime result is -1.
[0077] In the second embodiment:
[0078] This embodiment is experimental measurement data, using existing ultrasonic measurement instruments and equipment in the laboratory, the experimental platform is built, the casing model is damaged processing such as Figure 2 As shown in the figure, 8 damages are processed in a week: 20mm and 40mm in diameter, 4 damages in each, and the wall thickness of the damage is 3.36mm, 5.36mm, 6.36mm and 7.36mm. Through the Ethernet remote program control six-axis positioning motion system, the automatic movement measurement of ultrasonic instrument is realized, and the experimental data is evaluated for wall thickness damage.
[0079] The specific implementation steps are as follows:
[0080] (1) The ultrasonic measurement instrument emits ultrasonic pulse vertically to the inner wall of the casing. In the measurement process, the center axis of the instrument rises along the casing direction, the rotation angle is set to 1.5°, and a circle of measurement is performed at a fixed depth, 240 waveform data are measured in a circle, and the waveform Wave is measured and scanned at different depths in turn.
[0081] (2) The first wave arrival time ArriveTime of different azimuth pulse echo waveform and the opposite direction (angle difference 180°) first wave arrival time OppositeTime are extracted by using long and short time window method. The average value AverageTime of the sum of ArriveTime and OppositeTime at the same depth (i.e. continuous one week measurement) is calculated.
[0082] (3) The speed of sound in the medium in the casing is calculated. The casing diameter Dcasing, the probe rotation track diameter D of the ultrasonic measurement instrument, the average value AverageTime calculated from the first wave arrival time and the corresponding opposite direction first wave arrival time, and the ultrasonic propagation speed V are calculated. As shown in Figure 3 The AverageTime=ArriveTime+OppositeTime, and the ultrasonic propagation speed formula is
[0083]
[0084] The result of the change of ultrasonic propagation speed with depth is shown in Figure 4 Due to the processing of different wall thickness damages on the casing at some depths, the speed calculation error at some depths is large, therefore, when selecting the medium sound speed in the experimental data, the good section of the casing section is selected, and the average value of the sound speed calculated from the experimental data is 1480.1m / s.
[0085] (4) The measured waveform Wave is preprocessed, and the sound source function is determined, as shown in Figure 5The time corresponding to the maximum value of the single-channel waveform PeakTime is first found, the waveform is subjected to Fourier transform FFT, and the center frequency f and the corresponding main period T of the waveform are extracted. The corresponding sequence is extracted within the time range [PeakTime-T, PeakTime+T] before and after the maximum value of the waveform as the sound source function Source of the ultrasonic instrument.
[0086] (5) Calculate the cross-correlation of the waveform and the sound source function. Wave and Source are used for calculation, the Source data is shifted, multiplied with the waveform data corresponding to the sum, and the cross-correlation result CorreWave is obtained.
[0087] (6) Envelope of CorreWave is calculated and low-pass filtered. The envelope EnvelopeWave of CorreWave is calculated using Hilbert transform, as shown in Figure 6 、 7 The maximum absolute value is normalized, and a corresponding Butterworth low-pass filter is designed for low-pass filtering.
[0088] (7) Locate the wave peak of EnvelopeWave, that is, locate the two possible reflection waves in the received waveform. First, locate the maximum wave peak value Peak1 of the waveform, and find the second largest wave peak value Peak2 before and after the maximum value of the waveform. If the position of Peak1 appears in front of Peak2, the value of Peak2 is subjected to threshold judgment, and the threshold is set to 0.15. If the value is lower than the threshold, it is considered that there is no second largest value; if the position of Peak1 appears behind Peak2, no operation is performed.
[0089] (8) Whether there is a second largest value Peak2. If there is no Peak2, continue to step (9); if there is Peak2, the located Peak1 and Peak2 are the two peak values of the waveform, as shown in Figure 8 The time difference DeltaTime corresponding to the two peak values is calculated, and step (10) is jumped to.
[0090] (9) Calculate the time span TimeWidth of the waveform descending to 20% of the maximum value of the waveform. If TimeWidth is greater than a certain period, there are two wave peaks and the two wave peaks overlap, the influence of the maximum value of the waveform is removed, the two maximum values Peak1 and Peak2 of the waveform are found, and the time difference DeltaTime corresponding to the two peak values is calculated; if TimeWidth is less than a certain period, it can be considered that the waveform only has one wave peak, and the DeltaTime result is-1.
[0091] (10) Calculate the damage thickness Thick. According to the two-peak time difference DeltaTime and the ultrasonic propagation speed V in the casing medium, the damage thickness is Thick = DeltaTime x V. The experimental data evaluation results are shown in Figure 9 As shown in the figure, the wall thickness damage degree can be quantitatively evaluated by the color depth of the damage, and the damage wall thickness of the adjacent two damages is the same, and the evaluation results are consistent with the processed damage size.
[0092] In a third embodiment:
[0093] This embodiment is actual measurement data, and the ultrasonic instrument is used to measure in the actual working well, and the actual data is quantitatively evaluated for damage wall thickness
[0094] The specific implementation steps are as follows:
[0095] (a) The ultrasonic measuring instrument emits ultrasonic pulse vertically to the inner wall of the casing. During the measurement, the center axis of the instrument rises along the casing direction, the rotation angle is set to 6°, and a circle of measurement is performed at a fixed depth, 60 waveform data are measured in a circle, and the waveform Wave is measured and scanned at different depths in turn.
[0096] (b) The first wave arrival time ArriveTime of the pulse echo waveform in different directions is extracted by using the long-short time window method, and the first wave arrival time OppositeTime of the opposite direction (angle difference 180°) is extracted. The average value AverageTime of the sum of ArriveTime and OppositeTiem at the same depth (i.e. continuous one-week measurement) is calculated.
[0097] (c) The sound speed of the casing medium is calculated. The casing diameter Dcasing, the probe rotation track diameter D of the ultrasonic measuring instrument, and the average value AverageTime calculated from the first wave arrival time of the pulse echo and the first wave arrival time of the opposite direction are used to calculate the ultrasonic propagation speed V. As shown in Figure 3 The AverageTime = ArriveTime + OppositeTime, and the ultrasonic propagation speed formula is
[0098]
[0099] The ultrasonic propagation speed changes with depth as shown in Figure 10 As shown in the figure, due to the existence of the casing coupling section in the actual well, there are a few abnormal values of the sound speed at some depths, therefore, when selecting the medium sound speed in the actual data, the influence of the coupling section on the extraction of the sound speed is removed, and the average value of the sound speed calculated from the experimental data is 1343.7 m / s.
[0100] (d) The measured waveform Wave is preprocessed to determine the sound source function. As shown inFigure 11 As shown, first find the time PeakTime corresponding to the single-channel waveform maximum value, perform Fourier transform FFT on the waveform, extract the center frequency f and the corresponding main period T of the waveform. Extract the corresponding sequence in the time range [PeakTime-T, PeakTime+T] before and after the waveform maximum value as the sound source function Source of the ultrasonic instrument.
[0101] (e) Calculate the cross-correlation of the waveform and the sound source function. Use Wave and Source to calculate, shift the Source data, multiply the corresponding waveform data to get the cross-correlation result CorreWave.
[0102] (f) Envelope the CorreWave and perform low-pass filtering. Use Hilbert transform to calculate the envelope EnvelopeWave of CorreWave, as shown in Figure 12 、 13 , perform maximum absolute value normalization, and design a corresponding Butterworth low-pass filter for low-pass filtering.
[0103] (g) Locate the wave peak of EnvelopeWave, that is, locate the two possible reflection waves in the received waveform. First locate the maximum wave peak value Peak1 of the waveform, find the second largest wave peak value Peak2 before and after the waveform maximum value, if the position of Peak1 appears in front of Peak2, then the value of Peak2 is threshold judged, set the threshold value to 0.15, and if it is lower than the threshold value, it is considered that there is no second largest value; if the position of Peak1 appears behind Peak2, then no operation is performed.
[0104] (h) Whether there is a second largest value Peak2. If there is no Peak2, continue step (i); if there is Peak2, the located Peak1 and Peak2 are the two peak values of the waveform, as shown in Figure 14 , calculate the time difference DeltaTime corresponding to the two peak values, and jump to step (j).
[0105] (i) Calculate the time span TimeWidth of the waveform falling to 20% of the waveform maximum value. If TimeWidth is greater than a certain period number, there are two wave peaks and the two wave peaks overlap, remove the influence of the waveform maximum value, find the two maximum values Peak1 and Peak2 of the waveform, and calculate the time difference DeltaTime corresponding to the two peak values; if TimeWidth is less than a certain period number, it can be considered that the waveform only has one wave peak, and the DeltaTime result is-1.
[0106] (j) calculating the damage thickness Thick. According to the two-peak time difference DeltaTime and the ultrasonic propagation speed V in the casing medium, the damage thickness is Thick = DeltaTime x V, and the experimental data evaluation results are shown in Figure 15 The wall thickness damage degree can be quantitatively evaluated by the color depth of the damage, and the left graph is the evaluation result of a non-serious damage well section, and the right graph is the evaluation result of a serious damage well section, which can be used as a reference for the maintenance of an actual well.
[0107] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.
Claims
1. A method for quantitatively evaluating a casing wall thickness damage, characterized by, The method comprises the following steps: Step S1: install the ultrasonic measuring instrument to emit ultrasonic pulses, during the measurement, the central axis of the ultrasonic measuring instrument rises along the direction of the casing, and the waveforms Wave are measured according to a fixed circumferential resolution and axial resolution; Step S2: calculate the ultrasonic propagation speed V of the medium in the casing; Step S3: pre-process the measured waveforms Wave to determine the sound source function Source of the ultrasonic instrument; Step S4: calculate using the measured waveforms Wave and the sound source function Source, shift the sound source function Source data, multiply and sum corresponding to the waveform data to obtain the cross-correlation result CorreWave of the waveforms Wave and the sound source function Source; Step S5: envelope the cross-correlation result CorreWave and perform low-pass filtering, locate the maximum peak value Peak1 and the second maximum peak value Peak2 of the two reflection waves that may appear in the received waveforms, and calculate the time difference DeltaTime corresponding to the two peak values; Step S6: according to the time difference DeltaTime of the two wave peaks and the ultrasonic propagation speed V in the casing medium, calculate the damage thickness Thick, and the calculation formula is: Thick = DeltaTime x V.
2. The method for quantitative evaluation of the wall thickness damage of a sleeve according to claim 1, characterized in that, The ultrasonic measuring instrument comprises an ultrasonic probe, which emits ultrasonic pulses perpendicular to the inner wall of the casing.
3. The method for quantitative evaluation of the wall thickness damage of a sleeve according to claim 1, characterized in that, The step S2 specifically comprises the following sub-steps: Step S21: use the long-short time window method to extract the first wave arrival time ArriveTime and the opposite direction first wave arrival time OppositeTime of the different azimuth pulse echo waveforms, calculate the average value AverageTime of the sum of the first wave arrival time ArriveTime and the opposite direction first wave arrival time OppositeTime of the continuous one-week measurement at the same depth, and the average value AverageTime is expressed as: AverageTime = ArriveTime + OppositeTime; Step S22: based on the casing diameter Dcasing and the probe rotation track diameter D of the ultrasonic measuring instrument, the average value AverageTime calculated based on the first wave arrival time and the opposite direction first wave arrival time corresponding thereto is used to obtain the ultrasonic propagation speed V, and the calculation formula is:
4. The method for quantitative evaluation of the wall thickness damage of a sleeve according to claim 1, characterized in that, The determination of the sound source function Source of the ultrasonic instrument in the step S3 is specifically: find the time PeakTime corresponding to the maximum value of the single-channel waveform, perform Fourier transform FFT on the waveform, extract the center frequency f and the corresponding main period T of the waveform; extract the corresponding sequence in the time range [PeakTime-T, PeakTime+T] before and after the waveform maximum value, and define it as the sound source function Source of the ultrasonic instrument.
5. The method for quantitative evaluation of the wall thickness damage of a sleeve according to claim 1, characterized in that, The low-pass filtering in the step S5 is specifically: use Hilbert transform to calculate the envelope EnvelopeWave of the cross-correlation result CorreWave, perform maximum absolute value normalization, and at the same time, set a corresponding Butterworth low-pass filter to perform low-pass filtering.
6. The method for quantitative evaluation of the wall thickness damage of a sleeve according to claim 5, characterized in that, The positioning of the peak value in the step S5 specifically comprises: Locate the maximum peak value Peak1 of the waveform, find the second largest peak value Peak2 before and after the maximum value of the waveform; If the position of the maximum peak value Peak1 appears in front of the second largest peak value Peak2, the value of the second largest peak value Peak2 is threshold judged, the threshold is set to 0.15, and if it is lower than the threshold, it is considered that there is no second largest peak value; If the position of the maximum peak value Peak1 appears behind the second largest peak value Peak2, no operation is performed, and the step S6 is jumped to.
7. The method for quantitative evaluation of the wall thickness damage of a sleeve according to claim 6, characterized in that, The step S5 further includes: if there is no second largest peak value, calculating the time span TimeWidth of the waveform descending to 20% of the maximum value of the waveform, specifically including: If the time span TimeWidth is greater than a preset period, there are two wave peaks and the two wave peaks overlap, the influence of the maximum value of the waveform is removed, the two maximum values Peak1 and Peak2 of the waveform are repositioned, and the time difference DeltaTime corresponding to the two peak values is calculated; If TimeWidth is less than a certain period, it is considered that there is only one wave peak, and the output DeltaTime result is-1.
Citation Information
Patent Citations
Ultrasonic nondestructive testing device and method
CN102183582A
Ultrasonic detecting method of defects in thick-wall composite tubular structure
CN105388212A